1,2,4-Triazole

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1,2,4-triazole
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1,2,4-Triazole
Names
Preferred IUPAC name
1H-1,2,4-Triazole
Other names
1,2,4-Triazole pyrrodiazole
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.005.476 Edit this at Wikidata
UNII
  • InChI=1S/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5) checkY
    Key: NSPMIYGKQJPBQR-UHFFFAOYSA-N checkY
  • InChI=1/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5)
    Key: NSPMIYGKQJPBQR-UHFFFAOYAZ
  • N1C=NC=N1
Properties
C2H3N3
Molar mass 69.00725
Appearance white solid
Density 1.439 g/cm3
Melting point 120 to 121 °C (248 to 250 °F; 393 to 394 K)
Boiling point 260 °C (500 °F; 533 K)
very soluble
Acidity (pKa) 10,3
Basicity (pKb) 11,8
Hazards
Flash point 140 °C (284 °F; 413 K)
Related compounds
Related compounds
1,2,3-triazole imidazole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

1,2,4-Triazole (as ligand in coordination compounds, Htrz abbreviation is sometimes used) is one of a pair of

molecular formula C2H3N3, called triazoles, which have a five-membered ring of two carbon atoms and three nitrogen atoms. 1,2,4-Triazole and its derivatives find use in a wide variety of applications.[1]

Structure and properties

1,2,4-Triazole is a planar molecule. The C-N and N-N distances fall into a narrow range 136 - 132 picometers, consistent with the aromaticity.[2] Although two tautomers can be envisioned, only one exists practically speaking.

1,2,4-Triazole is

amphoteric, being susceptible to both N-protonation and deprotonation in aqueous solution. The pKa of 1,2,4-triazolium (C2N3H4+) is 2.45. The pKa of the neutral molecule is 10.26.[3]

Synthesis and occurrence

Portion of the structure of {[Fe(triazolate)(triazole)2](BF4)}n.[4]

1,2,4-Triazoles can be prepared using the Einhorn–Brunner reaction or the Pellizzari reaction. Unsubstituted 1,2,4-triazole can be prepared from thiosemicarbazide by acylation with formic acid followed by cyclization of 1-formyl-3-thiosemicarbazide into 1,2,4-triazole-3(5)-thiol; oxidation of the thiol by nitric acid or hydrogen peroxide yields 1,2,4-triazole.[5]

1,2,4-Triazoles are featured in many kinds of drugs.

plant growth regulator paclobutrazol.[9] Triazolate is a common bridging ligand in coordination chemistry.[10]

References

  1. doi:10.1021/cr60210a001
    .
  2. doi:10.1107/S010876818300258X
    .
  3. ISBN 978-0-08-096518-5
    .
  4. doi:10.1002/ejic.201201121
    .
  5. doi:10.15227/orgsyn.040.0099
    .
  6. S2CID 9313180
    .
  7. PMID 26286663
    .
  8. PMID 22902032
    .
  9. S2CID 134517280
    .
  10. doi:10.1016/S0010-8545(00)00266-6
    .
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